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CDCUN1208LP register content after POR

Johan Huge
Prodigy 10 points
Other Parts Discussed in Thread: CDCUN1208LP

Hi,

In my project I use a CDCUN1208LP in I2C mode. A input clock of 60Mhz is applied permanantly.

My problem is, when i supply the device, the outputs clocks are present. When I dump the outputs registers values after the POR, i read evertime 0x18 for all registers, witch explain why i have a clock in all outputs. But the datasheet explain, the content of these register is 0x0 after POR.

Could you help me about that?

I dont need clock on the output after POR, because it could damage an other device.

I know program the CDCUN1208LP and I know stop its outputs clocks. but the time of the programmation is too long in my case. 

  • 0
    TI__Mastermind 24205 points

    Hi Johan,

    Couple of things:

    1) Ideally we should not have the input voltage higher than Vdd+0.5 (Page 4 of the datasheet). So applying an input to the device before the supply is available is not recommended

    2) Looks like you are using the Host Mode of operation. In this mode, INSEL Input Pin Mux control shoud still be available. Connect this input pin to ground using a weak pull down resistor (100k) to select IN1. Apply your input to IN2. Also connect a strong pull-up ~1K to Vdd on INSEL so that when the power supply ramps the selected output will be IN2 and the outputs will be available. When the supply is not avialable to the part, the selected input buffer will be IN1 (which should be properly terminated), and the outputs will be disabled

    Regards

    Arvind Sridhar